Tropical Storm KARINA

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TROPICAL STORM KARINA DISCUSSION NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
800 PM PDT TUE AUG 19 2014
Deep convection with cloud tops colder than -80C has redeveloped
near Karina's center, and convective banding features have improved
during the past 6 hours now that the cyclone is moving over a ridge
of warmer sea surface temperatures. The result is that intensity
estimates from both TAFB and SAB have increased to a consensus
T3.0/45 kt, so the initial intensity is being held at 45 kt.
Karina is moving slowly westward or 275/04 kt. There remains no
significant change to the previous reasoning. Karina is forecast to
stall and/or make a small loop in 24 to 48 hours when steering
currents are forecast to weaken considerably. By 72 hours and
beyond, the cyclone is expected to come under the influence of
southwesterly steering flow generated by the very large circulation
of Tropical Storm Lowell, which is currently located well to the
east of Karina. The NHC model guidance is actually in very good
agreement on the development of this rather complex synoptic flow
pattern and eventual interaction between the two tropical cyclones.
The only significant difference since the previous advisory is that
the model guidance envelope has shifted well to the east. The
official forecast track follows suit and has been shifted slightly
to the east, but not nearly as far east as the consensus model TVCE
due to the uncertainty in which direction Karina will move after the
cyclone stalls and/or completes a looping motion.
The outflow from Tropical Storm Lowell is expected to affect
Karina within the next 12 hours, producing modest easterly to
southeasterly vertical wind shear across the cyclone through 72
hours. The result is that little change in intensity is forecast,
although there will likely be some small fluctuations in the
intensity during that time. By 72 hours and beyond, the shear is
expected to steadily increase as Karina moves closer to Tropical
Storm Lowell, which should induce steady weakening. By Day 5,
Karina will be moving over 22C SSTs, causing the system to
degenerate into a post-tropical remnant low pressure system. The NHC
intensity forecast is just an update of the previous advisory and
closely follows the consensus intensity model ICON.
FORECAST POSITIONS AND MAX WINDS
INIT 20/0300Z 15.9N 135.3W 45 KT 50 MPH
12H 20/1200Z 15.9N 135.8W 45 KT 50 MPH
24H 21/0000Z 16.0N 136.2W 45 KT 50 MPH
36H 21/1200Z 15.8N 136.2W 45 KT 50 MPH
48H 22/0000Z 15.6N 135.7W 45 KT 50 MPH
72H 23/0000Z 16.7N 134.0W 40 KT 45 MPH
96H 24/0000Z 19.5N 130.5W 30 KT 35 MPH
120H 25/0000Z 24.0N 128.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
Forecaster Stewart
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